/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public ListNode deleteDuplicates(ListNode head) {
    	if (head == null) {
    		return null;
    	}
    	ListNode cur = head;
    	while (cur.next != null) {
    		if (cur.val == cur.next.val) {
    			cur.next = cur.next.next;
    		} else {
    			cur = cur.next;
    		}
    	}
    	return head;
    }
}